• This was achieved in two steps. First, trees from
permanent plots were classified using cluster analysis in five different stages. Second,
discriminant analysis was applied to confirm the robustness of the groups generated by
cluster analysis and to allow the assignment of new stone pine trees to one of the five
development stages. Each development stage was associated with an average cone production.

• A methodology for selecting candidates for plus trees was suggested. Trees belonging to
the 90th quartile or higher for the number of cones per crop and for cone crop weight were
identified throughout the three years of the study.

• Trees were evaluated as potential
candidates for plus trees using the following variables: the number of cones, cone crop
weight and relative production capacity. The relative production capacity was defined as
the cone crop weight per square meter of the crown area.